The novel mutation p.Trp147Arg of the steroidogenic acute regulatory protein causes classic lipoid congenital adrenal hyperplasia with adrenal insufficiency and 46,XY disorder of sex development

Rare Types of Congenital Adrenal Hyperplasias Other Than 21-hydroxylase Deficiency

Although the most common cause of congenital adrenal hyperplasia (CAH) worldwide is 21-hydroxylase deficiency (21-OHD), which accounts for more than 95% of cases, other rare causes of CAH such as 11-beta-hydroxylase deficiency (11β-OHD), 3-beta-hydroxy steroid dehydrogenase (3β-HSD) deficiency, 17-hydroxylase deficiency and lipoid CAH (LCAH) may also be encountered in clinical practice. 11β-OHD is the most common type of CAH after 21-OHD, and CYP11B1 deficiency in adrenal steroidogenesis causes the inability to produce cortisol and aldosterone and the excessive production of adrenal androgens. Although the clinical and laboratory features are similar to 21-OHD, findings of mineralocorticoid deficiency are not observed. 3β-HSD deficiency, with an incidence of less than 1/1,000,000 live births, is characterized by impairment of both adrenal and gonadal steroid biosynthesis very early in life, with inadequate virilization in boys and varying degrees of virilization in girls. It may present with salt wasting crisis or delayed puberty in both genders. While 46,XY disorders of sex development is frequently observed in boys with 17-hydroxylase deficiency, immature pubertal development and primary amenorrhea are observed in girls due to estrogen deficiency throughout adolescence. Patients with LCAH, which develops due to steroidogenic acute regulatory protein deficiency, typically present with salt wasting in the first year of life. It is characterized by complete or near-complete deficiency of adrenal and gonadal steroid hormones and progressive accumulation of cholesterol esters in the adrenal gland.

Sex Hormones, Growth Hormone, and the Cornea

The growth and maintenance of nearly every tissue in the body is influenced by systemic hormones during embryonic development through puberty and into adulthood. Of the ~130 different hormones expressed in the human body, steroid hormones and peptide hormones are highly abundant in circulation and are known to regulate anabolic processes and wound healing in a tissue-dependent manner. Of interest, differential levels of sex hormones have been associated with ocular pathologies, including dry eye disease and keratoconus. In this review, we discuss key studies that have revealed a role for androgens and estrogens in the cornea with focus on ocular surface homeostasis, wound healing, and stromal thickness. We also review studies of human growth hormone and insulin growth factor-1 in influencing ocular growth and epithelial regeneration. While it is unclear if endogenous hormones contribute to differential corneal wound healing in common animal models, the abundance of evidence suggests that systemic hormone levels, as a function of age, should be considered as an experimental variable in studies of corneal health and disease.

A case report of pedigree of a homozygous mutation of the steroidogenic acute regulatory protein causing lipoid congenital adrenal hyperplasia

RATIONALE

Lipoid congenital adrenal hyperplasia (LCAH) is extremely rare, but is the most fatal form of congenital adrenal hyperplasia resulting from mutations in the steroidogenic acute regulatory protein (STAR) gene. LCAH arises from severe defects in the conversion of cholesterol to pregnenolone, the precursor of all steroids.

PATIENT CONCERNS

A case was reported that an 11-month-old Chinese girl who presented with a sex development disorder and hyponatremia. The clinical and genetic tests were carried out to confirm the diagnosis. The genogram of this case was also explored and analyzed. The girl presented with hyponatremia, decreased cortisol level, elevated adrenocorticotropic hormone level and female vulva despite a 46, XY karyotype. Enlarged adrenal glands and testicular-like tissue in the bilateral inguinal regions were detected with abdominal ultrasound. She was suspected of having LCAH, and definitive diagnosis was made after Sanger sequencing detected a homozygous frameshift variant c.707_708delins CTT (p.Lys236Thrfs*47) on exon 6 of the STAR gene.

DIAGNOSES

LCAH.

INTERVENTIONS

She was prescribed hydrocortisone 10 to 12 mg/m2 and 9a- fludrocortisone 100 mg/d.

OUTCOMES

Her skin hyperpigmentation and vomiting disappeared, and she had normal growth and development without adrenal crisis attacks. Her hormone and electrolyte levels remained normal, except for a persistently elevated ACTH level throughout 2 years of follow-up. At follow-up for 2 years, the patient is now 104.5 cm tall and weighs 23.3 kg at the age of 4 years old. Her plasma sodium and potassium concentration were normal. Her ACTH level is still elevated (1176 pg/mL). Her baseline sex hormone levels are testosterone <0.1 ng/dL and progesterone <0.08 ng/dL. The level of PRA (1.06 ng/mL per h) is within normal range.

LESSONS

This mutation was in accordance with previously reported gene mutations. The patient's parents were nonconsanguineous; her parents, paternal grandfather, and maternal grandmother were all found to be carriers of a STAR gene mutation. This 46 XY disorders of sex development case presented with adrenal insufficiency and female phenotype initially. The diagnosis was complicated depending on the clinical hormone workup. LCAH was confirmed by genetic tests and genogram of the family.

Disorders in the initial steps of steroid hormone synthesis

Steroidogenesis begins with cellular internalization of low-density lipoprotein particles and subsequent intracellular processing of cholesterol. Disorders in these steps include Adrenoleukodystrophy, Wolman Disease and its milder variant Cholesterol Ester Storage Disease, and Niemann-Pick Type C Disease, all of which may present with adrenal insufficiency. The means by which cholesterol is directed to steroidogenic mitochondria remains incompletely understood. Once cholesterol reaches the outer mitochondrial membrane, its delivery to the inner mitochondrial membrane is regulated by the steroidogenic acute regulatory protein (StAR). Severe StAR mutations cause classic congenital lipoid adrenal hyperplasia, characterized by lipid accumulation in the adrenal, adrenal insufficiency, and disordered sexual development in 46,XY individuals. The lipoid CAH phenotype, including spontaneous puberty in 46,XX females, is explained by a two-hit model. StAR mutations that retain partial function cause a milder, non-classic disease characterized by glucocorticoid deficiency, with lesser disorders of mineralocorticoid and sex steroid synthesis. Once inside the mitochondria, cholesterol is converted to pregnenolone by the cholesterol side-chain cleavage enzyme, P450scc, encoded by the CYP11A1 gene. Rare patients with mutations of P450scc are clinically and hormonally indistinguishable from those with lipoid CAH, and may also present as milder non-classic disease. Patients with P450scc defects do not have the massive adrenal hyperplasia that characterizes lipoid CAH, but adrenal imaging may occasionally fail to distinguish these, necessitating DNA sequencing.

Identification of five novel STAR variants in ten Chinese patients with congenital lipoid adrenal hyperplasia

Congenital lipoid adrenal hyperplasia (CLAH) is a rare autosomal recessive disorder caused by defective synthesis of all steroids. This disorder is characterized by 46,XY sex reversal, skin hyperpigmentation, early-onset adrenal crisis and enlarged adrenal with fatty accumulation. CLAH is caused by mutations in the STAR gene. The clinical features and STAR gene mutation spectrum of a large cohort of Chinese patients with CLAH were not reported previously. We performed clinical retrospective review and genetic analysis of the STAR gene in ten unrelated Chinese phenotypic female patients who were clinically diagnosed with CLAH and followed up in our hospital from 2006 to 2015. All ten patients, including two 46,XY females and eight 46,XX females, presented skin hyperpigmentation and early salt-wasting episode, and showed normal growth and development after steroid replacement treatment. Totally 20 mutant alleles containing 11 different STAR gene mutations were identified in these ten patients, including five novel variants (two missense and three null variants), all predicted to be pathogenic in bioinformatics analysis, and six mutations described in previous literature. Among these 11 mutations, a reported mutation c.772C>T and a novel variant c.707_708delinsCTT were most frequent, accounting for 35% and 15% of the total mutant alleles, respectively. This is the first report of a large Chinese cohort with CLAH, presenting the mutation spectrum of the STAR gene and two possible founder mutations in the Chinese population, which may contribute to better genetic counseling and prenatal diagnosis.